bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/scripts/context-analysis-suppression.txt b/scripts/context-analysis-suppression.txt
new file mode 100644
index 000000000..1c51b6153
--- /dev/null
+++ b/scripts/context-analysis-suppression.txt
@@ -0,0 +1,34 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# The suppressions file should only match common paths such as header files.
+# For individual subsytems use Makefile directive CONTEXT_ANALYSIS := [yn].
+#
+# The suppressions are ignored when CONFIG_WARN_CONTEXT_ANALYSIS_ALL is
+# selected.
+
+[thread-safety]
+src:*arch/*/include/*
+src:*include/acpi/*
+src:*include/asm-generic/*
+src:*include/linux/*
+src:*include/net/*
+
+# Opt-in headers:
+src:*include/linux/bit_spinlock.h=emit
+src:*include/linux/cleanup.h=emit
+src:*include/linux/kref.h=emit
+src:*include/linux/list*.h=emit
+src:*include/linux/local_lock*.h=emit
+src:*include/linux/lockdep.h=emit
+src:*include/linux/mutex*.h=emit
+src:*include/linux/rcupdate.h=emit
+src:*include/linux/refcount.h=emit
+src:*include/linux/rhashtable.h=emit
+src:*include/linux/rtmutex*.h=emit
+src:*include/linux/rwlock*.h=emit
+src:*include/linux/rwsem.h=emit
+src:*include/linux/sched*=emit
+src:*include/linux/seqlock*.h=emit
+src:*include/linux/spinlock*.h=emit
+src:*include/linux/srcu*.h=emit
+src:*include/linux/ww_mutex.h=emit